Egg Launcher!

A bit early for a culminating.. but here we are at the much overused "Build an Egg Launcher" project. The idea is to use surgical tubing (2ft) to launch an egg the farthest possible (the egg can crack, it doesn't matter). The only force allowed in this is the elastic force of the surgical tubing (you can stretch it out before hand). There is a maximum weight of 2.5kg.

Right now, I'm thinking along the lines of a Roman Ballista, though perhaps if the weight exceeds 2.5kg, I'll move onto just a regular crossbow..

There is, of course, the over-done slingshot that I'll resort to when all else fails. I was also trying to wrap my mind around a way to use the surgical tubing with centrifugal (or centrifical; God knows) force -- that is, to somehow wrap it around a pole, and have it spinning out.

Any ideas? I'm not looking for formulas at this point.. but perhaps just names of things I could research, or some original launching ideas.